Pull rocket shroud



July 20, 1 P. c. PETRE PULL ROCKE': SHROUD Filed May 17, 1961 2 %m G 111:--. F

July 20, 1965 c, PETRE 3,195,462

PULL ROCKET SHROUD Filed May 17, 1961 2 Sheets-Sheet 2 FIG.6. FIG].

INVENTOR. PHILIP C. PETRE fizz. p 6

ATTORNEYS United States Patent 3,195,462 PULL ROCKET SHROUD Philip C. Petr-e, Santa Barbara, Calif., assignor, by mesne assignments, to Aerojet-General Corporation, Aznsa, Calif., a corporation of Ohio Filed May 17, 1961, Ser. No. 110,754 3 Claims. (Cl. 102-49) This invention relates to an improved shroud structure for booster rockets employed with either ballistic or self-powered payloads.

In co-pending patent application Serial No. 9,649 filed February 18, 1960, for Gyro Pull Rocket, now US. Patent No. 3,067,682 issued December 11, 1962, there is disclosed a booster rocket motor rotatably mounted on a stem extending from the nose portion of a payload. The mounting is such that universal movement of the motor axis of rotation with respect to the stem axis can take place so that the direction of thrust of the motor may be maintained in a constant direction by gyroscopic action when the motor is rapidly spun even though the axis of the payload and stem may tilt with respect to the axis of rotation.

An important component in the above-described structure is a streamlined shroud secured to the stem itself and providing an aerodynamically streamlined envelope for the rotating motor.

Studies made of the pull rocket and payload combination together with the shroud when subjected to various acceleration, drag, and gravity forces existing during the boost phase, indicate that deviations from the desired flight path as a result of cross winds may be corrected in large par-t by mounting of the shroud itself.

It is accordingly a primary object of this invention to provide an improved shroud structure and mounting therefor in conjunction with booster pull rockets so designed that deviations from a flight path as a consequence of side winds and the like are minimized.

Briefly, the foregoing is attained by providing a free swiveling type shroud structure about the pull booster motor. This may be achieved by universally mounting the shroud itself to the stem portion supporting the motor. By properly locating the mounting point and center of gravity of the shroud with respect to the aerodynamic center of pressure, the shroud may be caused to inherently weather vane into the wind. In this instance, the center of gravity is coincident with the mounting or pivot point. The lift caused by the missile configuration can thus be reduced causing less drift or deviation from the desired flight path due to atmospheric movement of the air during the boost phase. An alternative to designing the center of gravity to be coincident with the pivot point is to locate the center of gravity forward of the pivot point of the shroud. In this instance, the shroud may be caused to inherently lift into a wind. This lift will tend to counteract the down wind component of drag and lift, thus offering a possibility to completely compensate for the atmospheric movement during the boost phase.

The free swiveling shroud structure is designed to be aerodynamically stable by locating the center of pressure aft of both the mechanical mounting or pivot point for the shroud and center of gravity of the shroud. The mechanical mounting or pivot point may be disposed between the center of pressure and center of gravity of the shroud, or the mechanical mounting point may be disposed to be coincident with the center of gravity.

A better understanding of this invention as well as various further features and advantages thereof will be had by now referring to the accompanying drawings, in which:

FIGURE 1 is a fragmentary perspective view broken BJQSAfiZ Patented July 20, 1965 away to show one means for universally mounting the shroud of this invention;

FIGURE 2 is a view similar to FIGURE 1 showing an alternative mounting means;

FIGURE 3 is a diagram useful in explaining the operation of the shroud in a horizontal plane during flight;

FIGURE 4 is a view similar to FIGURE 3 taken in a vertical plane; and,

FIGURES 5, 6, and 7 illustrate successive stages during the launching phase of a rocket employing the free swiveling shroud.

Referring first to FIGURE 1, there is shown the extreme fragmentary nose portion 10 of a payload arranged to be initially boosted by a pull rocket in the form of a spherical rocket chamber 11 including a plurality of nozzles as indicated at 12 and 13. The chamber 11 is universally mounted to a rigid stem 14 as by suitable bearings 15. The arrangement is such that the stem and payload axes may vary or tilt with respect to the resultant thrust direction or axis as a consequence of firing of the motor, the direction of the thrust being gyroscopically maintained constant by rapidly spinning the entire motor 11 about the stem. The advantages of this arrangement are fully set forth in the above-referred-to co-pending patent application, now US. Patent 3,067,682.

As shown in FIGURE 1, there is provided a shroud 16 generally in the shape of a paraboloid which, in accordance with the present invention, is mounted for free swiveling movement. In FIGURE 1, the mounting includes a first gimbal or yoke 17 secured at 18 to the stem 14 at its center and having its ends pivoted at 19 to diametrically opposite side of a second gimbal ring 20. The shroud 16 is in turn pivoted at 21 to opposite sides of the second gimbal ring 20 so that the respective pivot axes at 19 and 21 are .at right angles to each other, these axes intersecting at a point coinciding with the center of the universal mounting 15 for the motor 11. The shroud 16 is thus free swiveling about this point.

FIGURE 2 illustrates an alternative mounting means for the shroud 16. In this instance, the stem is modified as indicated at 14' to terminate in the universal mounting 15 for the motor 11. The shroud 16 is supported by .a stem portion 22 having one end secured to the shroud at 23 and its opposite lower end terminating in a ball and socket joint 24 immediately above the universal bearing 15. The socket portion of the joint is rigidly supported by the end of the stem 14'. By this arrangement, the center of swiveling action of the shroud 16 is disposed slightly above the center of the universal mounting for the motor '11.

As shown in both FIGURES 1 and 2, small fins such as indicated at 25 and 26 may be secured to the exterior of the shroud 16. These fins will augment the weather vaning effect of the shroud when the missile is airborne.

Referring now to FIGURE 3, the operation of the free swiveling shroud of this invention will be evident. FIG- URE 3 is taken in a horizontal plane with the payload 1t} and pull rocket 11 in flight. It is assumed that a cross wind W is directed against the shroud 16 from the right when considered in the horizontal plane corresponding to the plane of the drawing. This wind when considered relative to the moving shroud is given by the vector RW. The center point of mounting or swiveling action of the shroud 16 is indicated at M, the aerodynamic center of pressure at P, and the center of gravity of the shroud at G. The thrust axis of the motor 11 is indicated at T, the shroud axis is indicated at S, and the flight path tangent at F. The design of the shroud and the positioning of the centers of pressure, mounting, and gravity is such that the shroud will tend to reverse and thus compensate for deviation due to the cross wind W.

If it be assumed in FIGURE 3, for example, that the s,195,ae2

shroud axis S ini-tially lies between the flight path F and the thrust axis T, the sum of the moments acting on the shroud will be such as to tend to cause the shroud to rotate in a clockwise direction about its swiveling center M. As the shroud so rotates such that the shroud axis S passes the relative wind direction RW, the total sum of all of the moments acting will approach zero, and the shroud will reach a position of equilibrium, this position being the position shown in FIGURE 3. To realize the foregoing, it is only necessary to design the shroud so that the center of pressure P is sufficiently aft of the center of mounting M.

With the shroud in the position shown in FIGURE 3, the relative wind vector RW will strike the shroud itself to the left of its axis to provide a lift force which will tend to veer the nose portion of the shroud and thus the entire pull motor and payload to the right; that is, in a direction opposite to the deviation which would normally result from the wind vector W. Thus, such deviation from the desired flight path is compensated for by the free swiveling shroud.

Similar conditions occur in the vertical flight plane as shown in FIGURE 4. As in the case of FIGURE 3, the shroud axis will lift into the relative wind, which, in the case of FIGURE 4, is below the flight path line, since the thrust is normally at an angle above the desired flight path to compensate for the Weight.

The behavior of the free swiveling shroud during launching of the missile will be understood by referring to FIG- URES 5, 6, and 7. FIGURE 5 illustrates the position of the shroud 16 just prior to actual launching. This is an unstable position for the shroud when the center of gravity G of the shroud is ahead of the center of mounting M. The shroud is preferably, however, held in this position as by any suitable mechanical means which may, if desired, be secured to the launcher frame itself.

As the missile is fired, the acceleration experienced by the shroud and acting at the center of mounting will tend to hold the shroud 16 in its initial position even though the mechanical latch has been released since the center of gravity of the shroud is forward of the action of acceleration at the point M. This inertia effect will gradually be counteracted upon by the aerodynamic effects on the shroud so that the shroud will rotate in a clockwise direction as indicated in passing from FIGURE 6 to FIGURE 7 to a point of equilibrium wherein cross winds and the like as described heretofore will have a minimum effect and the motion of the shroud will be in such a manner as to self-correct any undesired deviations resulting from the aerodynamic action.

While the center of gravity of the shroud structure has been disclosed as being disposed ahead of the center of mounting M, it may be located so as to coincide with the center of mounting M or even be aft of the mounting. As mentioned, however, for aerodynamic stability, it is important that the center of pressure be aft of the center of mounting M. The maximum degree of swiveling or tilting of the shroud may be determined by either a mechanical stop such as the periphery of the socket joint 24 in FIGURE 2 or by the action of gaseous exhaust from the rocket nozzles acting on the inside base portion of the shroud.

Modifications in the shape and mounting structure will occur to those skilled in the art. The shroud structure is therefore not to be thought of as limited to the specific embodiment set forth merely for illustrative purposes.

What is claimed is:

1. In a pull rocket including an elongated stem for connection at one end to a payload, thrust developing means disposed about said stem, a universal bearing mounting said thrust developing means to said stem for rotation thereabout to develop a gyroscopic action in response to rapid rotation of said thrust developing means for maintaining thrust direction, and a shroud in the shape of a paraboloid having an enlarged opening at its rear end and disposed about said thrust developing means in radially outwardly spaced relationship for connection to said stem, the improvement comprising means mounting said shroud on said stem for universal movement of said shroud about a given point disposed forwardly of the center of pressure of said shroud so that said shroud is enabled to pivot with respect to said stem and said thrust developing means in response to atmospheric movement of the air as the pull rocket is in flight to compensate therefor in maintaining a desired path of flight for the pull rocket.

2. In a pull rocket as defined in claim 1, wherein said universal mounting means for said shroud comprises a first elongated arcuately extending gimbal fixedly secured to said stem medially of the opposite ends of said first gimbal at a point on said stem disposed forwardly of said universal bearing, a second annular gimbal pivotally secured at a first pair of diametrically opposite pivot points thereon to the opposite ends of said first gimbal, a second pair of diametrically opposite pivot points on said second annual gimbal having an axis perpendicular to the axis of said first pair of pivot points, and said shroud being pivotally secured to said second annular gimbal at said second pair of pivot points, the axes of said first and second pairs of pivot points intersecting at a point coinciding with the center of said universal bearing.

3. In a pull rocket as defined in claim 1, wherein said universal mounting means for said shroud comprises a stem portion extending axially within the forward end portion of said shroud and being fixedly secured thereto at one end, the other end of said stem portion terminating in a ball, said stem having a socket on its end disposed forwardly of said universal bearing, and said socket receiving said ball for universal movement therein.

References Cited by the Examiner UNITED STATES PATENTS 2,594,766 4/52 Goddard 244 2,864,568 12/58 Ikard et al. 24414 3,067,682 12/62 Feldmann et al.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, CHESTER L. JUSTUS,

Examiners. 

1. IN A PULL ROCKET INCLUDING AN ELONGATED STEM FOR CONNECTION AT ONE END TO A PAYLOAD, THRUST DEVELOPING MEANS DISPOSED ABOUT SAID STEM, A UNIVERSAL BEARING MOUNTING SAID THRUST DEVELOPING MEANS TO SAID STEM FOR ROTATION THEREABOUT TO DEVELOP A GYROSCOPIC ACTION IN RESPONSE TO RAPID ROTATION OF SAID THRUST DEVELOPING MEANS FOR MAINTAINING THRUST DIRECTION, AND A SHROUD IN THE SHAPE OF A PARABOLOID HAVING AN ENLARGED OPENING AT ITS REAR END AND DISPOSED ABOUT SAID THRUST DEVELOPING MEANS IN RADIALLY OUTWARDLY SPACED RELATIONSHIP FOR CONNECTION TO SAID STEM, THE IMPROVEMENT COMPRISING MEANS MOUNTING SAID SHROUD ON SAID STEM FOR UNIVERSAL MOVEMENT OF SAID SHROUD ABOUT A GIVEN POINT DISPOSED FORWARDLY OF THE CENTER OF PRESSURE OF SAID SHROUD SO THAT SAID SHROUD IS ENABLED TO PIVOT WITH RESPECT TO SAID STEM AND SAID THRUST DEVELOPING MEANS IN RESPONSE TO ATMOSPHERIC MOVEMENT OF THE AIR AS THE PULL ROCKET IS IN FLIGHT TO COMPENSATE THEREFOR AND MAINTAINING A DESIRED PATH OF FLIGHT FOR THE PULL ROCKET. 